/**
 * ****************************************************************************
 * Spine Runtimes Software License Version 2
 *
 * Copyright (c) 2013, Esoteric Software All rights reserved.
 *
 * You are granted a perpetual, non-exclusive, non-sublicensable and
 * non-transferable license to install, execute and perform the Spine Runtimes
 * Software (the "Software") solely for internal use. Without the written
 * permission of Esoteric Software, you may not (a) modify, translate, adapt or
 * otherwise create derivative works, improvements of the Software or develop
 * new applications using the Software or (b) remove, delete, alter or obscure
 * any trademarks or any copyright, trademark, patent or other intellectual
 * property or proprietary rights notices on or in the Software, including any
 * copy thereof. Redistributions in binary or source form must include this
 * license and terms. THIS SOFTWARE IS PROVIDED BY ESOTERIC SOFTWARE "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL ESOTERIC SOFTARE BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 ****************************************************************************
 */
package sg.atom2d.game2d.graphics.anim.spine.skeleton;

import sg.atom2d.game2d.graphics.anim.spine.attachments.Attachment;
import sg.atom2d.game2d.graphics.anim.spine.attachments.BoundingBoxAttachment;

import sg.atom.utils.collection.Array;
import sg.atom.utils.collection.FloatArray;
import sg.atom2d.game2d.graphics.anim.spine.Slot;

public class SkeletonBounds {

    private float minX, minY, maxX, maxY;
    private Array<BoundingBoxAttachment> boundingBoxes = new Array();
    private Array<FloatArray> polygons = new Array();

    public void update(Skeleton skeleton, boolean updateAabb) {
        Array<BoundingBoxAttachment> boundingBoxes = this.boundingBoxes;
        Array<FloatArray> polygons = this.polygons;
        Array<Slot> slots = skeleton.slots;
        int slotCount = slots.size;
        float x = skeleton.getX(), y = skeleton.getY();

        boundingBoxes.clear();
        polygons.clear();
        polygons.ensureCapacity(slotCount);

        for (int i = 0; i < slotCount; i++) {
            Slot slot = slots.get(i);
            Attachment attachment = slot.attachment;
            if (attachment instanceof BoundingBoxAttachment) {
                BoundingBoxAttachment boundingBox = (BoundingBoxAttachment) attachment;
                boundingBoxes.add(boundingBox);

                polygons.size = boundingBoxes.size;
                FloatArray polygon = polygons.peek();
                if (polygon == null) {
                    polygons.set(polygons.size - 1, polygon = new FloatArray());
                }

                int vertexCount = boundingBox.getVertices().length;
                polygon.ensureCapacity(vertexCount);
                polygon.size = vertexCount;
                boundingBox.computeWorldVertices(x, y, slot.bone, polygon.items);
            }
        }

        if (updateAabb) {
            aabbCompute();
        }
    }

    private void aabbCompute() {
        float minX = Integer.MAX_VALUE, minY = Integer.MAX_VALUE, maxX = Integer.MIN_VALUE, maxY = Integer.MIN_VALUE;
        Array<FloatArray> polygons = this.polygons;
        for (int i = 0, n = polygons.size; i < n; i++) {
            FloatArray polygon = polygons.get(i);
            float[] vertices = polygon.items;
            for (int ii = 0, nn = polygon.size; ii < nn; ii += 2) {
                float x = vertices[ii];
                float y = vertices[ii + 1];
                minX = Math.min(minX, x);
                minY = Math.min(minY, y);
                maxX = Math.max(maxX, x);
                maxY = Math.max(maxY, y);
            }
        }
        this.minX = minX;
        this.minY = minY;
        this.maxX = maxX;
        this.maxY = maxY;
    }

    /**
     * Returns true if the axis aligned bounding box contains the point.
     */
    public boolean aabbContainsPoint(float x, float y) {
        return x >= minX && x <= maxX && y >= minY && y <= maxY;
    }

    /**
     * Returns true if the axis aligned bounding box intersects the line
     * segment.
     */
    public boolean aabbIntersectsSegment(float x1, float y1, float x2, float y2) {
        float minX = this.minX;
        float minY = this.minY;
        float maxX = this.maxX;
        float maxY = this.maxY;
        if ((x1 <= minX && x2 <= minX) || (y1 <= minY && y2 <= minY) || (x1 >= maxX && x2 >= maxX) || (y1 >= maxY && y2 >= maxY)) {
            return false;
        }
        float m = (y2 - y1) / (x2 - x1);
        float y = m * (minX - x1) + y1;
        if (y > minY && y < maxY) {
            return true;
        }
        y = m * (maxX - x1) + y1;
        if (y > minY && y < maxY) {
            return true;
        }
        float x = (minY - y1) / m + x1;
        if (x > minX && x < maxX) {
            return true;
        }
        x = (maxY - y1) / m + x1;
        if (x > minX && x < maxX) {
            return true;
        }
        return false;
    }

    /**
     * Returns true if the axis aligned bounding box intersects the axis aligned
     * bounding box of the specified bounds.
     */
    public boolean aabbIntersectsSkeleton(SkeletonBounds bounds) {
        return minX < bounds.maxX && maxX > bounds.minX && minY < bounds.maxY && maxY > bounds.minY;
    }

    /**
     * Returns the first bounding box attachment that contains the point, or
     * null. When doing many checks, it is usually more efficient to only call
     * this method if {@link #aabbContainsPoint(float, float)} returns true.
     */
    public BoundingBoxAttachment containsPoint(float x, float y) {
        Array<FloatArray> polygons = this.polygons;
        for (int i = 0, n = polygons.size; i < n; i++) {
            if (containsPoint(polygons.get(i), x, y)) {
                return boundingBoxes.get(i);
            }
        }
        return null;
    }

    /**
     * Returns true if the polygon contains the point.
     */
    public boolean containsPoint(FloatArray polygon, float x, float y) {
        float[] vertices = polygon.items;
        int nn = polygon.size;

        int prevIndex = nn - 2;
        boolean inside = false;
        for (int ii = 0; ii < nn; ii += 2) {
            float vertexY = vertices[ii + 1];
            float prevY = vertices[prevIndex + 1];
            if ((vertexY < y && prevY >= y) || (prevY < y && vertexY >= y)) {
                float vertexX = vertices[ii];
                if (vertexX + (y - vertexY) / (prevY - vertexY) * (vertices[prevIndex] - vertexX) < x) {
                    inside = !inside;
                }
            }
            prevIndex = ii;
        }
        return inside;
    }

    /**
     * Returns the first bounding box attachment that contains the line segment,
     * or null. When doing many checks, it is usually more efficient to only
     * call this method if
     * {@link #aabbIntersectsSegment(float, float, float, float)} returns true.
     */
    public BoundingBoxAttachment intersectsSegment(float x1, float y1, float x2, float y2) {
        Array<FloatArray> polygons = this.polygons;
        for (int i = 0, n = polygons.size; i < n; i++) {
            if (intersectsSegment(polygons.get(i), x1, y1, x2, y2)) {
                return boundingBoxes.get(i);
            }
        }
        return null;
    }

    /**
     * Returns true if the polygon contains the line segment.
     */
    public boolean intersectsSegment(FloatArray polygon, float x1, float y1, float x2, float y2) {
        float[] vertices = polygon.items;
        int nn = polygon.size;

        float width12 = x1 - x2, height12 = y1 - y2;
        float det1 = x1 * y2 - y1 * x2;
        float x3 = vertices[nn - 2], y3 = vertices[nn - 1];
        for (int ii = 0; ii < nn; ii += 2) {
            float x4 = vertices[ii], y4 = vertices[ii + 1];
            float det2 = x3 * y4 - y3 * x4;
            float width34 = x3 - x4, height34 = y3 - y4;
            float det3 = width12 * height34 - height12 * width34;
            float x = (det1 * width34 - width12 * det2) / det3;
            if (((x >= x3 && x <= x4) || (x >= x4 && x <= x3)) && ((x >= x1 && x <= x2) || (x >= x2 && x <= x1))) {
                float y = (det1 * height34 - height12 * det2) / det3;
                if (((y >= y3 && y <= y4) || (y >= y4 && y <= y3)) && ((y >= y1 && y <= y2) || (y >= y2 && y <= y1))) {
                    return true;
                }
            }
            x3 = x4;
            y3 = y4;
        }
        return false;
    }

    public float getMinX() {
        return minX;
    }

    public float getMinY() {
        return minY;
    }

    public float getMaxX() {
        return maxX;
    }

    public float getMaxY() {
        return maxY;
    }

    public float getWidth() {
        return maxX - minX;
    }

    public float getHeight() {
        return maxY - minY;
    }

    public Array<BoundingBoxAttachment> getBoundingBoxes() {
        return boundingBoxes;
    }

    public Array<FloatArray> getPolygons() {
        return polygons;
    }

    /**
     * Returns the polygon for the specified bounding box, or null.
     */
    public FloatArray getPolygon(BoundingBoxAttachment boundingBox) {
        int index = boundingBoxes.indexOf(boundingBox, true);
        return index == -1 ? null : polygons.get(index);
    }
}
